During the encapsulation technique the gelatin ribbon is typically pulled out from two sources into a product-loading station where the ribbons are thermally sealed with each other to isolate the product in between them, so that, as they swell up the product becomes trapped between the cavities formed by the roller casts facing each other, wherein the casts further comprise a die-like cutting rim that cuts out the excess gelatin and form the capsule. The gelatin excess is cut out by the interaction of two cutting rims of each one of the casts on the rollers.
As such, gelatin capsules are normally prepared using flexible and deformable gelatin in the form of a ribbon. To obtain the desired effect, gelatin may be mixed with other components to vary its characteristics in different manners for diverse applications, so the term gelatin is used in the present invention to encompass a range of gelatin-based compositions used for encapsulation processes.
Due to this flexibility and deformability, although several methods have been proposed to apply signs or symbols on the gelatin ribbon for them to appear on the resulting capsule, thus far it has been impossible to place specific signs on a gelatin ribbon for them to appear on a pre-determinable manner on the resulting capsule.
There are several alternatives to this gelatin capsule printing issue. The ones used more often involve a printing process wherein one of the gelatin ribbons is previously printed before the process proceeds towards the thermal sealing step.
In fact, US Document, U.S. Pat. No. 2,624,163 granted to Stirn, discloses a system to print colors, stripes, and legends on a gelatin film prior to the formation of gelatin capsules. US Document, U.S. Pat. No. 2,929,320 granted to Hansen et al., discloses a capsule-forming gelatin-film printing system that includes inking means applied prior to capsule formation. Also, the prior art discloses Great Britain Patent Application GB 9605891 granted to Cruttenden, related to a printing system that prints the gelatin ribbon during transportation, that is, before capsule filling and formation.
All the above documents involve printing on the gelatin ribbon prior to capsule formation, wherein previously inked rollers print the desired symbol or sign on the ribbon. The impression can be appreciated on the surface once the gelatin ribbon is encapsulated and the capsule is formed.
These printing apparatuses and processes are appropriate when the signs or symbols to be printed are sufficiently small with respect to the size of the capsule. Otherwise, during the capsule-formation process, the impressions may overlap with each other, or, in the worst case scenario, the impression may become diffuse as the gelatin ribbon expands during filling and thermal sealing.
There are some other printing systems where the capsule is printed using an inked roller after it has been formed. These systems are unsuitable because the capsule must be positioned in a certain way, snugly fit and ready for a correct printing, this making the process time-consuming, and thus, expensive.